Step 1 In a large bowl, whisk together the sour cream and mayonnaise until very smooth. Whisk in the garlic, onion, parsley, chives, dill, tarragon, lemon zest, vinegar, salt and chipotle pepper. Fold in the blue cheese. Season to taste with black pepper, and adjust the salt and vinegar if desired. Cover and chill until needed; the dip tastes best if the flavors are allowed to develop 2 to 3 hours before serving. The dip will keep, covered and refrigerated, up to three days.